Communications systems that utilize non-stationary users or relay sites require directional antennas to direct radio signals between stations. These wideband directional communications systems sometimes feature directionally agile phased array antennas (PAA). PAAs use an electrical means of steering a radio signal beam instead of mechanically moving the antenna. Steering the beam using electrical means is substantially faster than moving the antenna mechanically, and eliminates the error-inducing mechanical momentum of moving antennas. PAA's are one example of directionally agile antenna capable of steering a radio signal beam, and can be used by both moving and fixed stations.
Communications systems are designed to be as efficient as possible, both in terms of spectral efficiency and power efficiency. Moving stations require tracking systems to assist in directing radio signal beams. Tracking systems ensure that beams widths can be kept as narrow as possible. Narrow beam widths reduce the amount of power necessary for effective communication between stations, prevent unwanted parties from potentially receiving signals, and prevent overlap of signals onto spatially adjacent receivers, which is important for regulatory compliance.
Prior art tracking systems are generally constructed for continuous tracking operations and symmetric beams. In practice however, placement of the actual antennas on moving platforms often results in that expected continuity being interrupted, either due to maneuvering of either the source or the sender, by operation of external noise sources, or by intervening obstructions. These interruptions and interferences change the nature of the tracking signal, potentially corrupting the tracking signal and otherwise degrading the accuracy of the tracking capability. This in turn reduces the effective data capacity of line of sight data links between stations.